There shall be chosen by the qualified electors of the state at the times and places of choosing members of the legislature, a secretary of state, auditor, treasurer, and superintendent of public instruction, who shall have attained the age of twenty-five (25) years respectively, shall be citizens of the United States, and shall have the qualifications of state electors. They shall severally hold their offices at the seat of government, for the term of four (4) years and until their successors are elected and duly qualified. The legislature may provide for such other state officers as are deemed necessary.